Heretofore, in a linear motor drive conveyor, there has been provided a truck having a reaction plate secured on the lower surface thereof, said reaction plate opposing fixed primary members of a linear induction motor. Such a conveyor is described in copending application Ser. No. 202,951, filed June 6, 1988, assigned to the assignee of the present application, the disclosure of which is incorporated herein by reference. Although the linear motor drive conveyor is useful and suitable for high speed conveyance, such a conveyor has a drawback that in case it is used in the painting process of automotive bodies, it is essential to clean it periodically because paints tend to adhere on the top surfaces of the primary members and flow into clearances between the reaction plates and the primary members.